This invention generally relates to a cam bushing assembly for a cam braking system. More particularly, this invention relates to a removable, detachable multiple-component cam bushing assembly. The assembly fits on the brake spider as part of a cam braking system.
There are two main functions of a cam bushing assembly. The primary purpose of a cam bushing is to support the camshaft in a brake spider housing. A secondary purpose of a cam bushing assembly is to allow for lubrication of the camshaft so that it can freely rotate.
Broadly speaking, there are two known types of brake camshaft bushing assemblies. Each has its own disadvantages.
A first type has a bearing retainer portion either welded to a brake spider or formed integrally with the spider. The bushing is removably placed in the retainer. However, the retainer may sometimes wear, and require replacement. With this type of assembly, the entire spider must be replaced. Also, it is desirable to pivot the camshaft for removal. However, the camshaft cannot be pivoted in a non-removable retainer. Thus, to remove the camshaft in this type of assembly, the wheel hub must be removed. This is undesirable.
A second type of bearing assembly has a one-piece retainer/bushing bolted to the spider. With this assembly, the bushing is integral to the retainer and cannot be removed. This is undesirable since it would be cheaper to simply replace the bushing. Also, the retainer is typically bolted to the spider with a closely controlled torque. It would be desirable to not need to replace the retainer, and achieve the torque load every time the bushing wears.
One other disadvantage of the single piece cam bushing is insufficient flow of lubrication to the camshaft. The use of the fixed components makes formation of lubricant passages quite difficult.
The cam bushing assembly of the present invention overcomes the above problems of single piece cam bushings. In general terms, this invention discloses a cam bushing assembly that includes a bushing retainer having an aperture and a bushing disposed within the aperture. The bushing retainer is removably attached to the brake spider and the bushing is removably attached to the retainer.
The bushing assembly is serviceable in several ways. The bushing itself can be removed from the retainer without removing the retainer from the brake spider. This is advantageous because the bolts that fasten the retainer to the brake spider, which are torqued to a predetermined value, do not have to be removed. Alternatively, the whole bushing assembly can be removed by unfastening the bolts. Since each component is individually removable, maintenance costs and time are minimal.
These and other features of this invention can be best understood from the following specification and drawings. Moreover, the use of the two removable components facilitates the inclusion of lubricant grooves. Thus, the present invention also ensures good lubricant flow.
As further shown in FIG. 1, the bushing 24 has a width 70 less than the width 72 of the bushing retainer 22. Therefore, when assembled, the bushing 24 does not contact the entire inner retainer surface 36 of the bushing retainer 22, and a non-contacting surface 76 is provided on the opposing sides of the bushing 24. An annular seal 74 is secured on the non-contacting surface 76, creating a lubrication reserve 78 between the seal 74 and the bushing 24. The reserve 78 retains the lubricant proximate to the bushing 24, and the seal 74 prevents the lubricant from flowing away from the bushing 24.